Double-stator switched flux permanent magnet machines having low rotor pole numbers
In this paper, double-stator switched flux permanent magnet (DS-SFPM) machines having low rotor numbers and whose stator teeth and rotor pole numbers are relatively same is investigated. Quantitative comparison of their electromagnetic performance is also given. Two-dimensional finite element (2D-FEA) analysis is employed in the prediction of the developed machines’ performance. It is observed that the open circuit flux-linkage waveforms of the analysed machines having odd rotor poles are both symmetrical and sinusoidal in contrast to its even number rotor pole counterparts whose waveforms are asymmetrical, non-sinusoidal and unbalanced. More importantly, the developed machines with odd rotor pole numbers exhibit higher torque density than its even rotor pole equivalents.
Keywords: Harmonics, low rotor pole, PM usage, and unbalanced back-EMF.